Make sure that the deflection and tension of the alternator belt correspond to the nominal values.
Disconnect the wire from the negative battery terminal.
Install an ammeter between terminal B and terminal.
Connect the wire to the negative battery terminal.
Turn off all electrical consumers.
Start the engine and set the crankshaft speed to 2000–2500 min-1.
Measure the current at the generator output. Measurements are made on «hot» engine at an air temperature of 20°C and a voltage at the terminals of 13.5 V.
Current strength:
- at 1000 min–1 - 0–75 A;
- at 2000 min–1 - 0–98 A.
Switch on the following electrical consumers one after the other:
- headlights;
- heater fan motor;
- rear window heater.
Verify that the current at terminal B of the alternator gradually increases. If the current does not increase, repair or replace the alternator.